DEVELOPMENT OF ANTI-AIRWAY EPITHELIAL CELL SPECIFIC ANTIBODIES IN LUNG TRANSPLANT RECIPIENTS WITH BRONCHIOLITIS OBLITERANS SYNDROME

Abstract

192 Bronchiolitis obliterans syndrome (BOS) is the most common cause of morbidity and mortality after lung transplantation (LT). BOS is identified histologically by fibrosis of the lamina propria and lumen. Our studies indicate that development of anti-HLA class I antibodies (Ab) after LT plays an important role in the pathogenesis of BOS. This study was conducted to determine the role of other non-HLA Abs directed against AEC in BOS pathogenesis and to characterize their antigenic specificity. Sera from 15 BOS+ LT patients and 12 BOS- LT patients were obtained prior to LT and again at 12 months intervals post-LT. Anti-HLA Abs were detected by PRA-STAT ELISA. After absorption of anti-HLA Abs with human platelets, anti-airway epithelial cells (AEC), anti-endothelial cell (EC), and anti-monocyte specific Abs were measured by flow cytometric (FC) analysis using 5 pooled AEC, 5 pooled EC, and 5 pooled peripheral blood mononuclear cells, respectively. Ten of the 15 BOS+ patients developed anti-HLA Abs, while none of the 12 BOS− patients developed anti-HLA Abs. Four of the 15 BOS+ patients also developed specific anti-AEC Abs while only 1 of the BOS− patients developed anti-AEC Abs. Three of the 5 BOS+ patients who did not develop anti-HLA Abs showed development of the anti-AEC Abs. None of the patients developed anti-EC or anti-monocyte Abs. One anti-HLA-, BOS+ patient showed development of anti-AEC Abs at 12 months post-LT and remained positive until 72 months post-LT. Other anti-HLA-, BOS+ patient showed development of anti-AEC Abs at 48 months post-LT that fell to undetectable levels at 72 months post-LT. FC analysis with 4 kidney epithelial cell lines, the MRC-5 lung fibroblastic cell line, a bronchial smooth muscle cell line, and the HBL-100 breast epithelial cell line showed no reactivity. This indicates exclusive reactivity to AECs by these serum samples. Further FC analysis with 9 different AEC lines of one of the anti-AEC serum samples showed reactivity only to 6 AEC lines suggesting reactivity against an allelic antigenic system. A protein of approximately 140 kDa was immunoprecipitated by the anti-AEC Abs from a positive AEC line but not from a negative AEC line. The anti-AEC Abs induced proliferation, intracellular Ca2+ mobilization, and tyrosine phosphorylation of a 100 kDa and a 25 kDa proteins in the AEC line. These data indicate that specific anti-AEC Abs are developed after LT and they may play an important role in the pathogenesis of BOS by inducing AEC activation and possibly the secretion of various growth factors in situ.